Abstract
In the minimal supergravity model (MSUGRA), as the parameter increases, the charged Higgs boson and light bottom squark masses decrease, which can potentially increase contributions from , and loops in the decay . We update a previous QCD improved decay calculation to include in addition the effects of gluino and neutralino loops. We find that, in the MSUGRA model, loops involving charginos also increase, and dominate over , , and contributions for . We find for large values of that most of the parameter space of the MSUGRA model for is ruled out due to too large a value of branching ratio . For and large , most of parameter space is allowed, although the regions with the least fine-tuning (low and are ruled out due to too low a value of . We compare the constraints from to constraints from the neutralino relic density, and to expectations for sparticle discovery at CERN LEP2 and the Fermilab Tevatron colliders. Finally, we show that non-universal GUT scale soft breaking squark mass terms can enhance gluino loop contributions to decay rate even if these are diagonal.
- Received 9 December 1997
DOI:https://doi.org/10.1103/PhysRevD.58.015007
©1998 American Physical Society